Iwamura-jo Castle was located in the southeastern area of Mino Province in Japan. Its ruins can be found in the modern-day town of Iwamura in Ena District, Gifu Prefecture.
The castle was first founded in 1185 by Kato Kagekado who was the vassal or retainers of Minamoto-no Yoritomo and from the 13th to 16th centuries, it was in the fief of the Toyama clan. Toyama Kageto (who was the retainer of Oda Nobunaga) would be the of the Toyama's to ruler.
Siege of Iwamura
In 1572, after the Siege of Iwamura, Takeda Shingen took the castle and entrusted it to Akiyama Nobutomo. The widow of Toyama Kageto negotiated the castles surrender and her own marriage to Nobutomo - for protection.
From July to December 1575, Oda Nobunaga attacked and took the castle, and after a 6 month siege he promised Nobutomo safety and his life if he ended holding out. However he reneged on his word and had Nobutomo and his wife executed by hanging upside down - punishment usually reserved for traitors. Nobunaga would eventually become Shogun or military ruler of all Japan.
Nobunaga placed the castle under the command of Toyotomi Hideyoshi. Hideyoshi in turn transferred power of Iwamura Castle to Tamaru Tomotada. After the Battle of Sekigahara, it was occupied under Tokugawa rule by the Ogyu Daimyo from 1601 to 1638, by the Niwa clan from 1638 to 1702, and finally by the Ishikawa clan from 1702 until the end of the Tokugawa period in 1868.
In 1873 Iwamura Castle was dismantled under a castle abolishment law. Today some stone walls and a turret are what remains of the old castle. Today Iwamura Castle is considered in the top 3 examples of mountaintop castles in Japan.